Contribution of patchy reconnection to the ion-to-electron temperature ratio in the Earth’s magnetotail

The ion-to-electron temperature ratio is a good indicator of the processes involved in the plasma sheet.Observations have suggested that patchy reconnection and the resulting earthward bursty bulk flows(BBFs)transport may be involved in causing the lower temperature ratios at smaller radial distances during southward IMF periods.In this paper,we estimate theoretically how a patchy magnetic reconnection electric field can accelerate ions and electrons differently.If both ions and electrons are non-adiabatically accelerated only once within each reconnection,the temperature ratio would be preserved.However,when reconnection occurs closer to the Earth where magnetic field lines are shorter,particles mirrored back from the ionosphere can cross the reconnection region more than once within one reconnection;and electrons,moving faster than ions,can have more crossings than do ions,leading to electrons being accelerated more than ions.Thus as particles are transported from tail to the near-Earth by BBFs through multiple reconnection,electrons should be accelerated by the reconnection electric field more times than are ions,which can explain the lower temperature ratios observed closer to the Earth.

Inter-stage line ratio of He- and Li-like Ti emissions for the electron temperature measurement

Under coronal conditions, the steady state rate-equations are used to calculate the inter-stage line ratios between Li-like ls22p(2P3/2)→ls22s(2S1/2) and He-like ls2p(1P1)→1s2(1S0) transitions for Ti in the electronic temperature ranges from 0.1keV to 20 keV. The results show that the temperature sensitivities are higher at the electronic temperature less than 5000 eV and the temperature sensitivities will decrease with the increase of electronic temperature.

Effects of Finite Aspect Ratio and Noncircular Plasma Flux Surface on Electron Temperature Gradient Driven Modes

A gyrokinetic model with integral eigenmode equations is developed based on the local equilibrium of shaped tokamak plasmas. Effects of main geometric parameters （finite aspect ratio, elongation, triangularity, and Shafranov shift gradient） on the electrostatic electron temper- ature gradient （ETG） driven modes are investigated numerically. It is found that the finite aspect ratio has a general stabilizing effect, while the elongation can be either stabilizing or destabilizing, depending on the poloidal wavelength of the mode and other parameters. It is shown that a low aspect ratio enhances the stabilizing effect of elongation, and weakens its destabilizing effect as well.

Determining the Charge-to-Mass Ratio of the Electron

The aim of this lab was to determine an experimental value for the charge-to-mass ratio e/me of the electron. In order to do this, an assembly consisting of Helmholtz coils and a helium-filled fine beam tube containing an electron gun was used. Electrons were accelerated from rest by the electron gun at a voltage of 201.3 V kept constant across trials. When the accelerated electrons collided with the helium atoms in the fine beam tube, the helium atoms entered an excited state and released energy as light. Since the Helmholtz coils put the electrons into centripetal motion, this resulted in a circular beam of light, the radius of which was measured by taking a picture and using photo analysis. This procedure was used to test currents through the Helmholtz coils ranging from 1.3 A to 1.7 A in increments of 0.1 A. Using a linearization of these data, the experimental value for the charge-to-mass ratio of the electron was found to be 1.850 × 1011 C/kg, bounded between 1.440 × 1011 C/kg and 2.465 × 1011 C/kg. This range of values includes the accepted value of 1.759 × 1011 C/kg, and yields a percent error of 5.17%. The rather low percent error is a testament to the accuracy of this procedure. During this experiment, the orientation of the ambient magnetic field due to the Earth at the center of the apparatus was not considered. In the future, it would be worthwhile to repeat this procedure, taking care to position the Helmholtz coils in such a way to negate the effects of the Earth’s magnetic field on the centripetal motion of electrons.

Energy response correction for an electronic personal dosimeter using the channel ratio method

An electronic personal dosimeter mainly uses a Si-PIN photodiode as X-and gamma-ray detectors.The photon energy response of this instrument is inconsistent in the case of no correction,which seriously affects the accurate monitoring of personal dose equivalent H_p(10)parameters for radiation workers.For this reason,in this paper we propose a method of combining composite screen detection technology,multichannel measurement technology,and the channel ratio method to achieve accurate measurement of the personal dose equivalent parameters.According to China National Standard GB/T 13161-2003 and National Verification Regulation JJG 1009-2006,the instrument was tested in the energy range between 48 keV and 1.25 MeV.The experimental results showed that the difference of energy response to ^(137)C_S corrected by the new method was almost constant within ±6.0%,which fulfilled the ±30% requirement of GB/T 13161-2003 and JJG1009-2006.Meanwhile,the method proposed obtained energy information regarding the radiation field.

Modifying microstructures and tensile properties of Mg-Sm based alloy via extrusion ratio

Microstructure and tensile properties of a Mg-Sm-Zn-Zr alloy with various extrusion ratios(ERs)of 6.9,10.4 and 17.6 were systematically investigated.It was identified that,greater ER increased dynamic recrystallization(DRX)fraction and coarsened DRX grains,which further suggests weakened basal fiber texture for the studied alloy.This is mainly due to the rising temperature from massive deformation heat when hot-extrusion.As a result,greater ER corresponds to a decreased strength but improved ductility.Finally,transmission electron microscopy(TEM)observations reveal that the dominant intermetallic phase,Mg_(3)Sm,is metastable,and it will transform into Mg_(41)Sm_(5)during extrusion with high-ER.This transformation leads to the accumulation of surplus Sm and Zn atoms,which induces the precipitation of Sm Zn_(3)phase at the surface of Mg_(41)Sm_(5)matrix.

PERFORMANCE ANALYSIS OF AZIMUTH ELECTRONIC BEAM STEERING MODE SPACEBORNE SAR

Pointing angle and pattern of the antenna can be changed swiftly to actualize the azimuth beam scanning by using electronic beam steering, which makes the Synthetic Aperture Radar (SAR) system more flexible and achieve a high resolution or cover a long strip within short time span. When the pointing angle is steered away from boresight, some aberrations may appear on the antenna pattern, e.g., the grating lobe appears, the main lobe gain decrease, and antenna pattern broadens, e.g., the aberrations result in the worsening of system performance, and complicate the corresponding performance analysis method. Conventional computation methods of performance parameters do not account for the rapid change of the antenna pattern. It introduces remarkable errors when the scanning angle is large. In this paper, a method of calculating performance parameters is proposed for the beam steering mode, which achieves the parameters by the energy accumulation in time domain. Actually, the proposed method simulates the working process of SAR and obtains accurate performance parameters. Furthermore, we analyze the effects of the grating lobe on the Azimuth Ambiguity to Signal Ratio (AASR), and present the generic Pulse Repetition Frequency (PRF) choosing principle which can also prevent the ambiguous area from weighting by the grating lobe. Finally, the effect of the antenna configuration on the performance parameters is analyzed by a system example.

The intensity ratio I (557.7 nm)/I (427.8 nm) at Zhongshan Station in Antarctica

Auroral intensity ratios at Zhongshan Station in Antarctica on 8 April 1999 are studied, along with variations in pene- trated electron energy. Ratios of/（557.7 nm）/I （427.8 nm） during the quiet period were from 5 to 22, and I （630.0 nm） / I （427.8 rim） ranged from 1 to 2.76. These variations were not caused by changes of atomic oxygen concentration, but rather by penetrated electron energy variability, or other mechanisms. Ratios decreased sharply during the auroral substorm, ranging from 1.66--6.5 and 0.071-1, respectively, mainly because of the increase in penetrated electron energy. At the onset of the substorm, the ratios reached their minima. This means that penetrated electron energy was maximized. When the substorm weakened, the penetrated electron energy returned to the pre-substorm level.

The Mystery behind the Fine Structure Constant Contracted Radius Ratio Divided by the Mass Ratio? A Possible Atomist Interpretation

This paper examines various alternatives for what the fine structure constant might represent. In particular, we look at an alternative where the fine structure constant represents the radius ratio divided by the mass ratio of the electron, versus the proton as newly suggested by Koshy [1], but derived and interpreted here based on Haug atomism (see [2]). This ratio is remarkably close to the fine structure constant, and it is a dimensionless number. We also examine alternatives including the proton mass divided by the Higgs mass, which appears to be another possible candidate for what the fine structure constant might represent.

Statistical Modeling of the Influence of Electron Degeneracy on the Interatomic Interactions

It is shown that electrons forming simple and multiple covalent bonds may have different contribu-tions to the interatomic interactions due to the degeneracy of electron states. A simple relationship between the length of covalent bond, its order and atomic numbers of the interacting atoms is de-duced.

分布驱动式纯电动汽车电子差速控制策略研究

以轮毂电机直接驱动的分布驱动式电动车为研究对象,为解决汽车转向行驶稳定性和主动安全性的问题,对其电子差速控制策略进行研究。将汽车转向时的横摆稳定性和车轮滑动率相结合,基于动力学计算转矩输出,使用模糊控制算法确定变量范围并设计出模糊控制器,采用双移线和方向盘角阶跃两种输入工况,通过CarSim搭建整车仿真联合模型,对两种电子差速控制策略的对比分析及仿真验证。结果表明,采用DYC+S控制策略比采用DYC+T控制策略的性能更加优越,提高了整车的驾驶性能。

轮毂式电动汽车电子差速复合控制方法

为实现轮毂式电动汽车在弯道的稳定转向,解决传统控制方法对汽车行驶速度的局限性,提出一种高-低速复合电子差速控制方法。当汽车处于低速行驶状态时,根据Ackermann转向模型获取驱动轮期望转速,提出一种模糊PID控制方法,实现轮速的稳定跟踪;当汽车处于高速行驶状态时,以驱动轮的相对滑移率作为反馈控制量,提出一种基于模糊逼近的滑移率优化控制方法,无需建立精确的系统状态空间模型,同时根据LQR理论保证了汽车驱动轮相对滑移率最小。Matlab/Carsim联合仿真证明,所提出的高-低速复合控制方法能够使汽车在不同行驶速度下实现稳定转向。

小型磁选态铯原子钟性能测试数据的统计与分析

LIP Cs-3000是一种国产的小型磁选态铯原子钟,在时频计量、卫星导航等领域获得应用。对近期交付的LIP Cs-3000性能测试数据进行统计与分析,得到了准确度的分布与范围,同时得到了峰谷比、信噪比、Ramsey线宽等指标的分布。从理论上估计了铯原子钟输出信号的稳定度指标范围,验证了该范围与实际测量相符。同时对电子倍增器电压每日增幅进行了统计,结合装铯量给出了LIP Cs-3000铯钟倍增器寿命的分布。统计与分析结果不仅有助于磁选态铯钟的性能提高,也有助于其他小型铯原子钟的性能提升。

不同肉酱比鹿肉酱中关键挥发性有机化合物的判别分析

目的探究不同肉酱比对鹿肉酱中挥发性有机化合物(volatile organic compounds,VOCs)影响的差异性,并筛选不同肉酱比的关键性VOCs。方法利用电子鼻结合气相色谱-离子迁移谱法(gas chromatography-ion mobility spectrometry,GC-IMS)检测不同肉酱比加工的鹿肉酱样品中的香气类别及VOCs成分,通过计算偏最小二乘法判别(partial least squares discriminant analysis,PLS-DA)和正交-偏最小二乘法判别(orthogonal partial least squares discriminant analysis,OPLS-DA)分析变量重要性因子(variable important for the projection,VIP),筛选可区分不同肉酱比的鹿肉酱样品中差异性影响最关键的变量敏感物质及VOCs(VIP>1)。结果电子鼻传感器S3、S7、S9和S10对应的氨类、芳香族、硫化物和萜烯类、芳香族、硫化氢类、烷烃类等敏感物质是不同肉酱比的鹿肉酱样品中最关键的挥发类特征性气味;利用GC-IMS共检测出82种主要VOCs,筛选出33种关键差异性特征VOCs(VIP>1),与电子鼻的关键特征性香气检测结果一致。结论基于电子鼻和GC-IMS的主要特征香气标志物的聚类分析能够有效、全面、客观地对不同肉酱比的鹿肉酱中关键挥发性性气味和VOCs进行区分和评价。

阴极半径影响磁控法测量电子荷质比的理论研究

分析了磁控法测量电子荷质比实验中电子的动力学方程,给出了磁控法测量电子荷质比的理论计算公式;并利用动力学方程模拟计算了电子的运动轨迹,计算表明:在阴极半径不为零的情况下,电子运动呈现为旋转的多个心形线的交错曲线这一类周期运动.利用模拟计算,验证了我们所得到的理论公式与动力学方程模拟的实验结果基本一致,从而验证了所给出的理论公式是正确的,且具有普适性.

Microscopic Analysis of Cementitious Sand and Gravel Damming Materia

The mechanical properties of cementitious sand and gravel damming material have been experimentally determined by means of microscopic SEM(Scanning Electron Microscopy)image analysis.The results show that the combination of fly ash and water can fill the voids in cemented sand and gravel test blocks because of the presence of hydrated calcium silicate and other substances;thereby,the compactness and mechanical properties of these materials can be greatly improved.For every 10 kg/m^(3) increase in the amount of cementitious material,the density increases by about 2%,and the water content decreases by 0.2%.The amount of cementitious material used in the sand and gravel in these tests was 80-110 kg/m^(3),the water-binder ratio was 1-1.50.Moreover,the splitting tensile strength was 1/10 of the compressive strength,and the maximum strength was 7.42 MPa at 90 d.The optimal mix ratio has been found to be 50 kg of cement,60 kg of fly ash and 120 kg of water(C50F60W120).The related dry density was 2.6 g/cm^(3),the water content was 6%,and the water-binder ratio was 1.09.

自由电子激光制备高强度亚稳态氦原子和类氦离子

在少电子原子精密光谱测量中,产生高强度、单一量子态的氦原子和类氦离子是实验研究的关键,也是改善实验测量信噪比的决定性因素.本文提出利用自由电子激光获得高强度亚稳态氦原子和类氦离子的实验方案.激光的制备效率可以通过求解光和原子相互作用的主方程获得,根据拟建设的深圳自由电子激光装置的设计参数和实验条件,计算得到亚稳态He,Li^(+)和Be^(2+)的制备效率分别可达3%,6%和2%以上.与常见的气体放电和电子轰击等制备方法相比,激光激发产生亚稳态原子/离子不仅可以提高制备产率,也可以降低放电时产生的电子、离子以及光子等高能杂散粒子的影响.利用自由电子激光激发制备亚稳态氦原子和类氦离子有望应用于多个研究领域.

Unified Description of the Three Stable Particles in Self-Action Allows Determination of Their Relative Masses

The Dirac equation γμ(δμ-eAμ)Ψ=mc2Ψ describes the bound states of the electron under the action of external potentials, Aμ. We assumed that the fundamental form of the Dirac equation γμ(δμ-Sμ)Ψ=0 should describe the stable particles (the electron, the proton and the dark-matter-particle (dmp)) bound to themselves under the action of their own potentials Sμ. The new equation reveals that self energy is consequence of self action, it also reveals that the spin angular momentum is consequence of the dynamic structure of the stable particles. The quantitative results are the determination of their relative masses as well as the determination of the electromagnetic coupling constant.

一种MTW结构分子筛的合成及其二甲苯异构化反应性能

采用类似五元环中间体结构的烷基吡咯烷为模板剂,通过动态水热法在不同碱度比和硅铝比条件下合成了一种具有MTW拓扑结构的分子筛(LMTW),通过XRD、N_(2)吸附-脱附、SEM、Py-FTIR和电子晶体学等方法对分子筛的结构进行表征。以该分子筛为酸性组分,负载铂制备了转化型二甲苯异构化双功能催化剂(Pt/LMTW),使用微型活塞流反应器对催化剂的反应性能进行评价,并与Pt/REI-430催化剂的性能进行比较。实验结果表明,合成的LMTW分子筛具有和MTW分子筛一致的特征峰及相似的晶胞参数,合成过程中的碱度比和硅铝比会影响分子筛的孔道结构、比表面积及酸性等。与Pt/REI-430催化剂相比,制备的Pt/LMTW催化剂用于二甲苯异构化反应具有优异的性能。

鉴别电子烟中天然烟碱和合成烟碱的分析方法研究进展

烟碱是电子烟等新型烟草制品中的核心成分之一,烟碱有天然提取和化学合成两种来源方式,如何鉴别成为近年来的研究热点。综述了8种分析方法,主要包括烟碱异构体比例法和同位素法等,对各方法的优缺点进行了讨论,并探讨了其它可能的方法。烟碱异构体比例法包括旋光仪法、HPLC法、GC法、SFC法和NMR法等,具有简单、快速、定性定量等特点,可作为间接鉴别的方法;同位素法包括δ^(2)H、δ^(14)C、同位素模式法等,具有准确、高效、无需定量的特点,可作为直接鉴别的方法。采用上述多种方法同时确证电子烟中的烟碱来源,将大大提高结果的准确可靠性,为产品质量控制和市场监管提供技术参考。